A management shake-up at
Yahoo Inc.
has conferred more power on
Kathy Savitt,
a marketing executive who has quickly risen to become one of Chief Executive
Marissa Mayer's
most prominent and trusted lieutenants.

Ms. Savitt, who joined as chief marketing officer in 2012, added oversight of news and video to her remit in the wake of Ms. Mayer's firing of operating chief
Henrique de Castro
last month.

The promotion puts Ms. Savitt, 50 years old, at the helm of Yahoo's push into digital media and cements her status as a key architect in Ms. Mayer's plan to turn around the Internet portal.

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As Ms. Savitt works to rebuild Yahoo's image, she also hopes to turn around her own career following the failure of her social commerce startup, Lockerz Inc. The Seattle company, which rewarded visitors with iPads and other freebies in exchange for watching ads, burned through more than $50 million in venture capital funding over three years as it struggled to attract users and advertisers. Ms. Savitt left for Yahoo in September 2012, and last month Lockerz was sold to Chinese e-commerce player
Light In The Box Ltd.
for a fraction of the money investors put in, rendering the shares held by most employees and early backers worthless.

Through Yahoo and her recent friendship with Ms. Mayer, Ms. Savitt has a second chance to accomplish what she failed to do with Lockerz: Build a cool online brand with youth appeal.

As content chief at Yahoo, Ms. Savitt now oversees a broad portfolio that includes Yahoo News, one of the most visited news sites, and Yahoo Screen, a video portal with original programs and licensed reruns like "Saturday Night Live." She is tasked with stocking these sites with attractive content that pulls visitors in and keeps them viewing ads, and winning over more of the users that marketers covet: people between the ages of 18 and 24.

Ms. Savitt founded her first company, a public relations firm, in 1993 and sold it seven years later to advertising conglomerate IPG. She then spent four years at
Amazon.com Inc.,
where she rose to vice president of communications and led some of the company's earliest forays into streaming digital content, such as the online talk show "Amazon Fishbowl with Bill Maher." Her brother,
Andy Jassy,
now runs Amazon Web Services, the online retailer's hosting service estimated to generate $4 billion a year.

During a stint running e-commerce for teen clothing brand
American Eagle Outfitters,
Ms. Savitt observed that a powerful new wave of consumers she calls "Generation Z" was starting to influence marketing campaigns using
Twitter
and
Facebook.
This insight inspired her to found Lockerz in 2009.

Lockerz rewarded users with a virtual currency called PTZ for every time they logged on, for each video they watched (usually, ads), for products they bought and for completing tasks like inviting a friend to the site. The PTZ could be redeemed for discounts on desirable fashion goods, or during periodic giveaways of more expensive freebies like iPads. Revenue would come in two ways: Retailers would pay to promote their goods and Lockerz would take a cut of products sold on the site.

But users and advertisers didn't show up. And those iPads started to add up. At one point, Lockerz was burning through more than $1 million a month as it was generating little revenue, according to two people with knowledge of the company's finances. Ms. Savitt experimented with new approaches, and overhauled its design to look more like Pinterest Inc.

Ms. Savitt became known inside the company for her hard-charging management style and strict deadlines, according to former employees. "She is a no-nonsense person," said
Larry Li,
the former chief architect of Lockerz.

As Ms. Savitt struggled to turn Lockerz into a viable business, in 2011 she met Ms. Mayer, then a
Google Inc.
executive, at a Fortune magazine event honoring women in business. The pair remained in touch, and soon after Ms. Mayer became Yahoo's CEO in July 2012, she hired Ms. Savitt as chief marketing officer, citing in a news release her experience "building and refining well-loved consumer brands like Amazon, American Eagle Outfitters and Lockerz."

Mark Stabingas
became CEO of Lockerz, and Ms. Savitt stayed on the board as chairman.

At Yahoo, the new marketing chief quickly began to help shape the direction of Ms. Mayer's turnaround strategy. In a brainstorming meeting in the fall of 2012, Ms. Savitt suggested that Yahoo should be focused on "daily habits"—a phrase that had been part of Lockerz's mission statement. On Ms. Mayer's first earnings call with investors days later, the CEO proclaimed that Yahoo's goal was "to make the world's daily habits inspiring and entertaining." It has since become a common refrain from Yahoo.

Ms. Savitt aimed to court young users last year with On The Road, a two-month series of music concerts featuring performers like Macklemore and
Kendrick Lamar
playing in towns such as Madison, Wis., and Cincinnati. "We would pull into Cincinnati with two big purple buses," said
Lisa Licht,
a senior vice president at Yahoo who was hired by Ms. Savitt and helped run the music tour. People in towns they visited tended to remember Yahoo's brand 18% more than in towns where they didn't, Ms. Licht said. That's evidence, she believes, that the campaign improved Yahoo's image and influence and got more people to visit its pages.

The event also proved that Ms. Savitt could pull off a big media initiative. "She became a voice Marissa started to trust on topics involving media," said one former Yahoo executive who asked not to be named.

Ms. Savitt has tried to woo advertisers, who make up the bulk of the company's revenue. On Jan. 28, Yahoo reported its fourth-quarter revenue fell 1.7%, excluding commissions paid to partners for Web traffic—the fourth straight quarter without revenue growth and a sign that Yahoo hasn't yet managed to revive its image as a fading Internet brand in the eyes of advertisers, its most important customers.

She organized two annual events for ad executives—an April getaway to Turks and Caicos Islands for chief marketing officers, and an October summit in Rhode Island for marketing agencies—where Yahoo wines and dines prospective clients and pitches them on ways to reach its Web visitors.

Ms. Savitt's biggest coup came last month, when Ms. Mayer fired Mr. de Castro, and divvied up his responsibilities rather than finding a replacement. While senior vice president
Mike Kerns
was given oversight of developing new products for video, news and other media properties—what Yahoo staffers internally refer to as the "canvas"—Ms. Savitt was given oversight of media creation, or the "paint."

Some of Ms. Savitt's new paint was on display at January's Consumer Electronics Show in Las Vegas, where the executive organized Yahoo's keynote presentation featuring a live comedy sketch by "Saturday Night Live" cast members and a performance by singer
John Legend.
The event also showcased two newly acquired stars—TV news personality
Katie Couric
and former New York Times tech columnist
David Pogue.
Mr. Pogue reports to Ms. Savitt.

The same week as the CES conference, Light In The Box paid less than $10 million to acquire Lockerz, by then called Ador. Former employees, inquiring about the potential value of the shares they received while at Lockerz, have been told the stock is worthless. Funding terms dictated that only some shareholders including Kleiner Perkins Caufield & Byers and
Liberty Media Corp.
received a payout.

Many former employees—but not all—blame Ms. Savitt for the company's failure and resent her departure to Yahoo. "I don't know the reason why she left," said Mr. Li, the former Lockerz employee who is now a venture capitalist. "If I were her, I would stay to see it through."

Ms. Savitt has said she has learned from her experience at Lockerz and is applying some of those lessons to her new role.

"The differences between startups and turnarounds are very small," Ms. Savitt said at an October 2013 entrepreneurship summit hosted by Cornell University, her alma mater. "You have to take risks, in a way, because there may not be a tomorrow."